<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>子级元素属性</title>
  <style>
     .items-order {
        display: flex;
        justify-content: space-around;
        width: 600px;
        height: 200px;
        background-color: aquamarine;
     }

     .item {
       width: 100px;
       height: 100px;
       background-color: #ff5777;
       border: 1px solid #eee;
     }
     .order1 {
       order: -1;
     }
     .order2 {
       order: 2;
     }

     .flex-grow {
       flex-grow: 2;
     }

  </style>
</head>
<body>
  <div class="items-order">
    <div class="item order1">1</div>
    <div class="item order2">2</div>
    <div class="item flex-grow">3</div>
    <div class="item">4</div>
  </div>
</body>
</html>